13.4 GMC Premium Infotainment | Duramax 6.6L Turbo Diesel | AT4 Premium Plus Package | Head-Up Display | Power Retractable Assist Steps | Heated & Ventilated Front Seats | Bose Premium Audio | HD Surround Vision The 2025 GMC Sierra 2500 Heavy Duty AT4 Crew Cab 4WD delivers premium off-road performance and heavy-duty capability, featuring an Onyx Black exterior paired with an exclusive Jet Black and Kalahari accent interior. Powered by a Duramax 6.6L V8 Turbo Diesel engine mated to an Allison 10-speed automatic transmission, this truck is engineered for serious hauling with a 5,148 kg (11,350 lb) GVWR, a 3.42 rear axle ratio, an auto-locking rear differential, a 2-speed active electronic Autotrac transfer case, an integrated trailer brake controller, and a Gooseneck/5th Wheel Prep Package. Towing confidence is supported by a comprehensive Trailering Package featuring Hitch Guidance, Hitch View, a Bed View Camera, and Trailer Side Blind Zone Alert. The exterior profile is distinguished by animated LED projector headlamps, LED fog lamps, LED cargo bed lighting, power-folding and extending trailering mirrors, a spray-on bedliner, rain-sensing wipers, a front license plate kit, and the six-function GMC MultiPro Tailgate. The AT4 Premium Plus Package further enhances the exterior with a power sunroof, LED roof marker lamps, and power-retractable assist steps with LED perimeter lighting. Inside, the cabin offers a luxurious layout equipped with heated and ventilated front seats, heated second-row outboard seats, a heated leather-wrapped steering wheel, driver seat and mirror memory, dual-zone climate control, premium floor liners, a power-sliding rear window, a Universal Home Remote, and 120V AC power outlets in both the instrument panel and cargo bed. Technology and connectivity are anchored by a 13.4-inch GMC Premium Infotainment touchscreen with Google Built-In, wireless Apple CarPlay, wireless Android Auto, SiriusXM with 360L, remote vehicle start, wireless device charging, and a Bose premium sound system. Driving ease and safety are elevated by a multicolor 15-inch Head-Up Display, a Rear Camera Mirror, Adaptive Cruise Control, HD Surround Vision, Front and Rear Park Assist, and the Sierra HD Pro Safety suite including Automatic Emergency Braking, Forward Collision Alert, Front Pedestrian Braking, Lane Departure Warning, Rear Cross Traffic Alert, and the tactile Safety Alert Seat. Stock # T4257279A AMVIC LICENSED DEALER